Cambridge is typical of very early railway stations. Three designs seem to have been very common. (1) Termini with a platform either side and often extra roads in the middle (originals at Bristol, York and elsewhere). (2) Important through stations like Cambridge where a single long platform was split in two by a crossover. (3) Wayside stations where platforms were staggered either side of a level crossing.I always presumed that stations with massively long platforms were mostly for end-to-end trains on the same platform, not for a very long train - in some cases because there was only one main platform to use.
Wasn't Cambridge like that years back? And Gloucester? And Bournemouth?
Long platforms in other places appeared later - like Euston and Perth - for long trains.